Anionic Group Self-Doping as a Promising Strategy: Band-Gap Engineering and Multi-Functional Applications of High-Performance CO32–-Doped Bi2O2CO3

Oxygen Vacancies in Shape Controlled Cu2O/Reduced Graphene Oxide/In2O3 Hybrid for Promoted Photocatalytic Water Oxidation and Degradation of Environmental Pollutants

A novel shape controlled Cu₂O/reduced graphene oxide/In₂O₃ (Cu₂O/RGO/In₂O₃) hybrid with abundant oxygen vacancies was prepared by a facile, surfactant-free method. The hybrid photocatalyst exhibits an increased photocatalytic activity in water oxidation and degradation of environmental pollutants (methylene blue and Cr⁶⁺ solutions) compared with pure In₂O₃ and Cu₂O materials. The presence of oxygen vacancies in Cu₂O/RGO/In₂O₃ and the formation of heterojunction between In₂O₃ and Cu₂O induce extra diffusive electronic states above the valence band (VB) edge and reduce the band gap of the hybrid consequently. Besides, the increased activity of Cu₂O/RGO/In₂O₃ hybrid is also attributed to the alignment of band edge, a process that is assisted by different Fermi levels between In₂O₃ and Cu₂O, as well as the charge transfer and distribution onto the graphene sheets, which causes the downshift of VB of In₂O₃ and the significant increase in its oxidation potential. Additionally, a built-in electric field is generated on the interface of n-type In₂O₃ and p-type Cu₂O, suppressing the recombination of photoinduced electron-hole pairs and allowing the photogenerated electrons and holes to participate in the reduction and oxidation reactions for oxidizing water molecules and pollutants more efficiently.

The Gadolinium (Gd3+) and Tin (Sn4+) Co-doped BiFeO3 Nanoparticles as New Solar Light Active Photocatalyst

The process of photocatalysis is appealing to huge interest motivated by the great promise of addressing current energy and environmental issues through converting solar light directly into chemical energy. However, an efficient solar energy harvesting for photocatalysis remains a critical challenge. Here, we reported a new full solar spectrum driven photocatalyst by co-doping of Gd³⁺ and Sn⁴⁺ into A and B-sites of BiFeO₃ simultaneously. The co-doping of Gd³⁺ and Sn⁴⁺ played a key role in hampering the recombination of electron-hole pairs and shifted the band-gap of BiFeO₃ from 2.10 eV to 2.03 eV. The Brunauer-Emmett-Teller (BET) measurement confirmed that the co-doping of Gd³⁺ and Sn⁴⁺ into BiFeO₃ increased the surface area and porosity, and thus the photocatalytic activity of the Bi_0.90Gd_0.10Fe_0.95Sn_0.05O₃ system was significantly improved. Our work proposed a new photocatalyst that could degrade various organic dyes like Congo red, Methylene blue, and Methyl violet under irradiation with different light wavelengths and gave guidance for designing more efficient photocatalysts.

Steering photoinduced charge kinetics via anionic group doping in Bi2MoO6 for efficient photocatalytic removal of water organic pollutants

Carbonated doping and noble metal loading improved the rate of photogenerated charge carriers and robustly enhanced the photocatalytic properties of Bi₂MoO₆.

Br-Doped Bi2O2CO3 exposed (001) crystal facets with enhanced photocatalytic activity

Br-Doped Bi₂O₂CO₃ exposed (001) facets were synthesized using CTAB as a surfactant and dopant. The highly enhanced photocatalytic performance of Br-doped Bi₂O₂CO₃ is attributed to the synergistic effects of the doping of Br⁻ and the active exposed (001) crystal facet.

Promoted photoelectrocatalytic hydrogen evolution of a type II structure via an Al2O3 recombination barrier layer deposited using atomic layer deposition

The introduction of an Al₂O₃ recombination barrier layer at the interface between TiO₂ and CdSe can effectively improve the PEC hydrogen evolution performance.

Surface oxygen vacancy induced solar light activity enhancement of a CdWO4/Bi2O2CO3 core–shell heterostructure photocatalyst

A CdWO₄/Bi₂O₂CO₃ core–shell heterostructure photocatalyst was fabricated via a facile two-step hydrothermal process.

Investigation on the effect of an anion layer on photocatalytic activity: carbonate vs. oxalate

The separate [Bi₂O₂]²⁺ and CO₃²⁻ layers can greatly improve the charge separation efficiency.

In-Situ Hydrothermal Synthesis of Bi-Bi2O2CO3 Heterojunction Photocatalyst with Enhanced Visible Light Photocatalytic Activity

Bismuth containing nanomaterials recently received increasing attention with respect to environmental applications because of their low cost, high stability and nontoxicity. In this work, Bi-Bi₂O₂CO₃ heterojunctions were fabricated by in-situ decoration of Bi nanoparticles on Bi₂O₂CO₃ nanosheets via a simple hydrothermal synthesis approach. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to confirm the morphology of the nanosheet-like heterostructure of the Bi-Bi₂O₂CO₃ composite. Detailed ultrafast electronic spectroscopy reveals that the in-situ decoration of Bi nanoparticles on Bi₂O₂CO₃ nanosheets exhibit a dramatically enhanced electron-hole pair separation rate, which results in an extraordinarily high photocatalytic activity for the degradation of a model organic dye, methylene blue (MB) under visible light illumination. Cycling experiments revealed a good photochemical stability of the Bi-Bi₂O₂CO₃ heterojunction under repeated irradiation. Photocurrent measurements further indicated that the heterojunction incredibly enhanced the charge generation and suppressed the charge recombination of photogenerated electron-hole pairs.

Quantum dots in photocatalytic applications: efficiently enhancing visible light photocatalytic activity by integrating CdO quantum dots as sensitizers

The amalgamation of a wide optical band gap photocatalyst with visible-light-active CdO quantum dots (QDs) as sensitizers is one of the most efficient ways to improve photocatalytic performance under visible light irradiation.

Non-stoichiometric SnS microspheres with highly enhanced photoreduction efficiency for Cr(vi) ions

Sn²⁺ self-doped SnS microparticles were synthesized via a simple template-free hydrothermal route. The ability to tune the band structure while minimizing defect generation makes self-doped SnS an efficient photocatalyst for treating waste water.

Role of MoS2and WS2monolayers on photocatalytic hydrogen production and the pollutant degradation of monoclinic BiVO4: a first-principles study

MS₂/m-BiVO₄(010) heterostructures showed a high driving force for H₂evolution and pollutant degradation under simulated visible light irradiation.

Shape Evolution of Hierarchical W18O49 Nanostructures: A Systematic Investigation of the Growth Mechanism, Properties and Morphology-Dependent Photocatalytic Activities

Hierarchical tungsten oxide assemblies such as spindle-like structures, flowers with sharp petals, nanowires and regular hexagonal structures are successfully synthesized via a solvothermal reduction method by simply adjusting the reaction conditions. On the basis of the experimental results, it is determined that the reaction time significantly influences the phase transition, microstructure and photocatalytic activity of the prepared samples. The possible mechanisms for the morphology evolution process have been systematically proposed. Moreover, the as-prepared products exhibit significant morphology-dependent photocatalytic activity. The flower-like W₁₈O₄₉ prepared at 6 h possesses a large specific surface area (150.1 m²∙g⁻¹), improved separation efficiency of electron-hole pairs and decreased electron-transfer resistance according to the photoelectrochemical measurements. As a result, the flower-like W₁₈O₄₉ prepared at 6 h exhibits the highest photocatalytic activity for the degradation of Methyl orange aqueous solution. The radical trap experiments showed that the degradation of MO was driven mainly by the participation of h⁺ and •O₂⁻ radicals.

Crystal Growth, Structure, Resistivity, Magnetic, and Photoelectric Properties of One-Dimensional Selenometallate Ba2 BiFeSe5

Low-dimensional materials have attracted extensive research interest in recent years owing to their interesting structural chemistry and physical properties, which will greatly deepen our knowledge of these materials and could lead to additional breakthroughs in the future. Herein we have synthesized and characterized Ba₂ BiFeSe₅ , which adopts a quasi-one-dimensional structure and possesses some fascinating physical properties. The sharp divergences between the field-cooled (FC) and the zero-field-cooled (ZFC) data and the rather small magnetic moment per Fe³⁺ (0.07 μ_B ) strongly suggest that the title compound is weakly ferromagnetic with a high magnetic transition temperature above room temperature, which is controlled by competing super-exchange interactions within and between [FeBiSe₅ ]_∞ anionic ladders. Moreover, with its narrow bandgap of 0.95 eV, Ba₂ BiFeSe₅ shows photoelectric properties with a photocurrent density of approximately 30 mA cm² at 5 V. Our study demonstrates that Ba₂ FeBiSe₅ might be a new type of multifunctional material that deserves further investigation.

Efficient Visible-Light Photocatalytic Properties in Low-Temperature Bi-Nb-O System Photocatalysts

Low-temperature Bi-Nb-O system photocatalysts were prepared by a citrate method using homemade water-soluble niobium precursors. The structures, morphologies, and optical properties of Bi-Nb-O system photocatalysts with different compositions were investigated deeply. All the Bi-Nb-O powders exhibit appreciably much higher photocatalytic efficiency of photo-degradation of methyl violet (MV), especially for Bi-Nb-O photocatalysts sintered at 750 °C (BNO750), only 1.5 h to completely decompose MV, and the obtained first-order rate constant (k) is 1.94/h. A larger degradation rate of Bi-Nb-O photocatalysts sintered at 550 °C (BNO550) can be attributed to the synergistic effect between β-BiNbO4 and Bi5Nb3O15. Bi5Nb3O15 with small particle size on β-BiNbO4 surface can effectively short the diffuse length of electron. BNO750 exhibits the best photocatalytic properties under visible-light irradiation, which can be attributed to its better crystallinity and the synergistic effect between β-BiNbO4 and α-BiNbO4. The small amount of α-BiNbO4 loading on surface of β-BiNbO4 can effectively improve the electron and hole segregation and migration. Holes are the main active species of Bi-Nb-O system photocatalysts in aqueous solution under visible-light irradiation.

Defect Engineering of Bismuth Oxyiodide by IO3- Doping for Increasing Charge Transport in Photocatalysis

Defect engineering is regarded as one of the most active projects to monitor the chemical and physical properties of materials, which is expected to increase the photocatalytic activities of the materials. Herein, oxygen vacancies and IO₃^- doping are introduced into BiOI nanosheets via adding NaH₂PO₂, which can impact the charge carrier dynamics of BiOI photocatalysts, such as its excitation, separation, trap, and transfer. These oxygen-deficient BiOI nanosheets display attractive photocatalytic activities of gaseous formaldehyde degradation and methyl orange under visible light irradiation, which are 5 and 3.5 times higher than the BiOI samples, respectively. Moreover, the comodified BiOI also displayed superior cycling stability and can be used for practical application. This work not only develops an effective strategy for fabricating oxygen vacancies but also offers deep insight into the impact of surface defects in enhancing photocatalysis.

Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi₂O₂CO₃ with Enhanced Visible-Light-Driven Photocatalytic Activity

In this work, a series of novel flower-like Ag@AgCl/Bi₂O₂CO₃ were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi₂O₂CO₃ and enhanced the absorption band of pure Bi₂O₂CO₃. The photocatalytic activities of the Ag@AgCl/Bi₂O₂CO₃ samples were determined by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The Ag@AgCl (10 wt %)/Bi₂O₂CO₃ composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %)/Bi₂O₂CO₃) and pure Bi₂O₂CO₃, respectively. Bisphenol A (BPA) was also degraded to further prove the degradation ability of Ag@AgCl/Bi₂O₂CO₃. Photocurrent studies indicated that the recombination of photo-generated electron–hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi₂O₂CO₃ and Ag@AgCl nanoparticles. Trapping experiments indicated that O₂⁻, h⁺ and Cl° acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi₂O₂CO₃ composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCl/Bi₂O₂CO₃ was proposed.

pH-regulated template-free assembly of Sb4O5Cl2 hollow microsphere crystallites with self-narrowed bandgap and optimized photocatalytic performance

Sb₄O₅Cl₂ hollow microspheres with self-narrowed bandgap and optimized photocatalytic performances are synthesized via a facile template-free method. It is found that the crystal structure and morphology of Sb₄O₅Cl₂ crystallites are strongly dependent on the pH values of precursors. Nano-sized irregular-cuboids assembled Sb₄O₅Cl₂ micro-particles and hollow microspheres can be synthesized at pH 1 and 2, whereas individual Sb₄O₅Cl₂ micro-belts become to form when the pH is higher than 3. The irregular-cuboids assembled Sb₄O₅Cl₂ micro-particles and hollow microspheres exhibit self-narrowed bandgap and higher light absorption ability compared with individual Sb₄O₅Cl₂ micro-belts. The photoelectrochemical measurements show that the assembled Sb₄O₅Cl₂ hollow microsphere crystallites prepared at pH 2 exhibit enhanced carrier density, improved separation efficiency of electron-hole pairs and decreased electron-transfer resistance. As a result, the irregular-cuboids assembled Sb₄O₅Cl₂ hollow microspheres prepared at pH = 2 exhibit the highest photocatalytic activity for the degradation of gaseous iso-propanol (IPA) and Rhodamine B (RhB) aqueous solution. The good photocatalytic activity of Sb₄O₅Cl₂ sample prepared at pH = 2 may be caused by the synergistic effect of its higher light absorption, the decreased electron-transfer resistance, the suppressed recombination of photogenerated electrons and holes, and the increased surface area.

Visible/near-IR-light-driven TNFePc/BiOCl organic-inorganic heterostructures with enhanced photocatalytic activity

Although semiconductor photocatalysis has been reported for more than 40 years, the spectral response is still focused on the region of UV-Visible and it is seldom extended to more than 600 nm. In this work, visible/near-IR-light-driven 2,9,16,23-tetranitrophthalocyanine iron (FeTNPc)/bismuth oxychloride (BiOCl) organic-inorganic heterostructures have been synthesized by a two-step solvothermal method. The obtained products were characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron and transmission microscopy, energy dispersive X-ray spectrometer, UV-vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption, and electrochemical measurements. The photocatalytic activity for the decomposition of methyl orange and bisphenol A solution can be significantly improved under visible/near-IR-light irradiation. Through detecting the main oxidative species by trapping experiments, the results show holes and ˙O2(-) radicals are majorly and minorly responsible for photodegradation respectively. What's more, the FeTNPc/BiOCl composite photocatalyst still retained the photocatalytic activity after three cycle measurements.

Fabrication of BiOBrxI(1-x) photocatalysts with tunable visible light catalytic activity by modulating band structures

A series of BiOBrxI(1-x) solid solutions were explored as novel visible light-sensitive photocatalysts. These BiOBrxI(1-x) solid-solution photocatalysts grew into two-dimensional nanoplates with exposed (001) facets and possessed continuously modulated band gaps from 2.87 to 1.89 eV by decreasing the Br/I ratio. The photocatalytic activities of these samples were measured, and the samples exhibited visible light-driven activities for the degradation of Rhodamine B (RhB). In particular, BiOBr0.8I0.2 exhibited the highest activity for the degradation of RhB. This result could be attributed to the balance between the effective light absorption and adequate redox potential. Additionally, investigations into the photocatalytic mechanism showed that the photodegradation of RhB over BiOBr0.8I0.2 solid-solution photocatalysts involved direct holes oxidation, in which the reaction that dominated during photocatalysis was determined by the potential of the valence band. Furthermore, a high stability in the photocatalytic activity of BiOBr0.8I0.2 was demonstrated by the cycling photocatalytic experiment and long-term irradiation, which might offer opportunities for its practical application as a catalyst.

Sulfur-doping synchronously ameliorating band energy structure and charge separation achieving decent visible-light photocatalysis of Bi2O2CO3

Sulfur doping simultaneously endows the wide-band-gap Bi₂O₂CO₃ promoted band energy structure and charge separation achieving enhanced visible-light photocatalytic performance for dye degradation and NO removal.

g-C3N4/Bi4O5I2 2D–2D heterojunctional nanosheets with enhanced visible-light photocatalytic activity

The 2D–2D heterojunctional g-C₃N₄/Bi₄O₅I₂ nanosheets were successfully constructed based on band gap engineering design. It exhibits high visible-light-driven photocatalytic activity for degradation of RhB and NO removal.

Synthesis of morphology-controlled bismutite for selective applications

Bismutite (Bi₂O₂CO₃) possessing diverse morphologies, namely, nanosheets, nanodiscs and nanoplatelets, was synthesized by a simple controllable method shows excellent materials as adsorbents and photocatalysts for wastewater treatment with supercapacitor activities for energy applications.

The effect of iron doping on the photocatalytic activity of a Bi2WO6–BiVO4composite

The formation of Fe-doped Bi₂WO₆–BiVO₄composites could improve the separation efficiency of photogenerated electron–hole pairs, then increasing its photocatalytic activity.

A self-sacrifice template route to iodine modified BiOIO3: band gap engineering and highly boosted visible-light active photoreactivity

In this work we demonstrate the continuously adjustable band gap and visible-light photocatalysis activation of WBG BiOIO₃via iodine surface modification.

Photocatalytic degradation of two different types of dyes by synthesized La/Bi2WO6

Parameters, such as inorganic ions and pH have different effects on the photocatalytic removal of X-3B and RhB using La/Bi₂WO₆.

Crystal and electronic structures, and photoluminescence and photocatalytic properties of α-EuZrS3

Novel crystalline α-EuZrS₃ shows Eu²⁺ photoluminescence and is photocatalytically active towards the decomposition of methylene blue under visible light or simulated sunlight irradiation.

Mild synthesis of {001} facet predominated Bi2O2CO3 clusters with outstanding simulated sunlight photocatalytic activities

Bi₂O₂CO₃ clusters built up of ultrathin nanosheets with predominated {001} facets were facilely synthesized via a template-free hydrothermal strategy at a mild temperature of 60 °C and exhibit excellent photocatalytic activity.

Band gap and Schottky barrier engineered photocatalyst with promising solar light activity for water remediation

A novel nanophotocatalyst of Mo- and S-doped TiO₂(Mo,S-codoped TiO₂) was synthesizedviaa modified sol–gel method in conjunction with photochemical reduction. The nanophotocatalyst showed great potential for environmental applications.

An efficient visible-light photocatalyst made from a nonpolar layered semiconductor by grafting electron-withdrawing organic molecules to its surface

The UV-light responsive Bi₂O₂(HCOO)₂ (BFM) becomes an efficient visible-light photocatalyst when it is chemically modified with 4-substituted electron-withdrawing thiophenolates ⁻S-C₆H₄Z.

The Polymerization Effect on Synthesis and Visible-Light Photocatalytic Properties of Low-Temperature β-BiNbO4 Using Nb-Citrate Precursor

Low-temperature β-BiNbO4 powders (denoted as Low-β) were prepared by citrate and Pechini methods using homemade water-soluble niobium precursors. The addition of ethylene glycol and the resultant polymerization effect on the synthesis and visible-light photocatalytic performance of β-BiNbO4 powders were fully investigated. The polymerization effect is beneficial to lower the phase formation temperature and obtain smaller particle catalysts. Both methods can synthesize catalysts with excellent performance of visible-light degradation of methyl violet (MV). The Low-β BiNbO4 powder prepared by citrate method shows better degradation rate of about 1 h to decompose 80 % of MV and also displays good photocatalytic stability. The photodegradation of MV under the visible-light irradiation followed the pseudo-first-order kinetics according to the Langmuir-Hinshelwood model, and the obtained first-order rate constant and half-time are 2.85 × 10(-2) min(-1) and 24.3 min, respectively. The better photocatalytic performance of BiNbO4 powders prepared by citrate method can be attributed to its smaller band gap and better crystallinity.

Topochemical transformation of low-energy crystal facets to high-energy facets: a case from Bi2O2CO3 {001} facets to β-Bi2O3 {001} facets with improved photocatalytic oxidation of NO

Photocatalytically active β-Bi₂O₃ nanosheets exposed with active {001} facets were facilely prepared through annealing Bi₂O₂CO₃ with thermal stable {001} facets.